Chaetoceros turingii sp. nov. (Bacillariophyceae): morphological and molecular description of a new species from the Gulf of Naples, Italy

In the present study we describe and illustrate a new species in the genus Chaetoceros, C. turingii sp. nov., from the Gulf of Naples, Italy. Colonies have a brush-like appearance due to the apparent randomness in seta orientation. The defi ning feature of this species is the regular pattern of narrow ridges on the exterior of the terminal valve face, which is visible in electron microscopy. In addition, a petallike collar is present at the base of each intercalary seta. Its nuclear-encoded 18S rDNA and partial 28S rDNA sequences were resolved in a clade with C. anastomosans, C. dayaensis, C. cf. vixvisibilis as well as with three other Chaetoceros species still in need of description. The new species is compared with morphologically similar species, and their diff erences are discussed.